Fluid-handling apparatus with corrosion-erosion coating and method of making same

ABSTRACT

Inlet surfaces of a fluid-handling apparatus, such as a heat exchanger, are often prone to corrosion and erosion due to the high velocities of incoming fluid. The present disclosure includes a fluid-handling apparatus with a plurality of wetted surfaces of which a first portion is corrosion-erosion prone and a second portion is non-corrosion-erosion prone. The first portion is coated with a corrosion-erosion coating that is harder than the first portion. Less than all of the wetted surfaces are coated.

TECHNICAL FIELD

The present invention relates generally to fluid-handling apparatuses,and more specifically to heat exchangers with a corrosive-erosionresistant coating and a method of making same.

BACKGROUND

There are various uses for heat exchangers known in the art. Forinstance, heat exchangers, often referred to as charge air coolers, usea coolant to cool compressed air exiting a turbocharger before the airis injected into an engine. In commercial or pleasure marine crafts, seawater is often used as the coolant. The sea water will flow into a seawater inlet manifold before flowing into a plurality of sea waterpassages, and the air will flow into an air inlet manifold beforeflowing into a plurality of air passages. The sea water passages aregenerally oriented perpendicularly to the air passages such that theheat within the air can be exchanged with sea water through walls of thesea water and the air passages. The sea water passages and the airpassages are defined by a core of the heat exchanger. The sea water willincrease in temperature and the air will decrease in temperature as thesea water and air simultaneously pass through the core of heatexchanger.

Using sea water as the coolant can present a challenge due to the seawater's corrosive nature and tendency to contain abrasives such as sandand silt and other forms of deposits including sea weeds, sea shellfragments, animal components, etc. As the sea water flows from the inletmanifold into the plurality of smaller sea water passages, the flow ofthe sea water is turbulent. Thus, the sea water will directly contact ata relatively high velocity inlet surfaces defining the sea water inletmanifold before flowing into the sea water passages. Due to the highvelocity and the corrosive nature of the sea water, the sea watercontacting the inlet surfaces will impinge the surfaces. The impingementcan cause corrosion and erosion, and thus, damage the surfaces of theinlet manifold, including a core surface defining inlets of the seawater passages. Over time, the damage can lead to holes, causing leakageof the sea water and, thus, premature failure of the heat exchanger. Forinstance, the corrosion and erosion can create holes in the surfacesseparating the hot air passages and the sea water inlet manifold orpassages, causing leaking of the sea water into the air passages.

One method known in the art of avoiding heat exchanger failure due toinlet surface corrosion-erosion and impingement is to use robustmaterials that offer corrosion-erosion resistance. For instance, a heatexchanger set forth in U.S. Pat. No. 5,323,849, issued to Korczynski,Jr. et. al., on Jun. 28, 1994, includes sea water wetted heat exchangercomponents that are made from corrosion and erosion-resistant materials.Although the Korczynksi heat exchanger includes corrosion anderosion-resistant sea water inlet surfaces, the heat exchanger alsoincludes other components, such as the tubes defining the sea waterpassages, made from corrosion-erosion resistant materials. However, thetubes are less prone to corrosion and erosion than the inlet surfaces.The sea water contacting the inlet surfaces is turbulent; whereas, thesea water flow through the tubes is generally laminar. The turbulentflow causes more impingement which leads to corrosion and erosion thandoes the laminar flow.

Manufacturing heat exchanger components from corrosion anderosion-resistant materials can be more costly than using traditionalmaterials. Further, the corrosion-erosion resistant materials canintroduce a heat transfer penalty due to their reduced thermalconductivity. Most of the heat transfer occurs through the materialseparating the air and sea water passages, which is also where there isthe least amount of impingement and corrosion-erosion related problemsdue to the flow of the sea water. Thus, by manufacturing all of the seawater wetted components out of corrosion-erosion resistant materials,rather than just the corrosion-erosion prone sea water inlet surfaces,the cost of the heat exchanger and the heat transfer penalty isunnecessarily increased while potentially also reducing heat transferperformance.

The present disclosure is directed at overcoming one or more of theproblems set forth above.

SUMMARY OF THE INVENTION

According to one aspect of the present disclosure, a fluid-handlingapparatus includes a an apparatus body including a plurality of wettedsurfaces of which a first portion is corrosion-erosion prone and asecond portion is non-corrosion-erosion prone. The first portion of thewetted surfaces is coated with a corrosion-erosion resistant coatingthat is harder than the first portion. Less than all of the wettedsurfaces are coated.

In another aspect of the present disclosure, an engine system withmarine applications includes an engine fluidly connected to a heatexchanger. The heat exchanger defines a sea water inlet that is fluidlyconnected to a plurality of wetted surfaces of which a first portion iscorrosion-erosion prone and a second portion is non-corrosion-erosionprone. The first portion is coated with a corrosion-erosion resistantcoating that is harder than the first portion. Less than all of thewetted surfaces are coated.

In yet another aspect of the present disclosure, a heat exchanger ismade by assembling a plurality of components to include a plurality ofwetted surfaces. Corrosion-erosion prone wetted surfaces aredistinguished from non-corrosion-erosion prone surfaces. Thecorrosion-erosion prone wetted surfaces are coated with acorrosion-erosion resistant coating that is harder than thecorrosion-erosion prone wetted surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an engine system, according tothe present disclosure;

FIG. 2 is a sectioned side diagrammatic representation of a heatexchanger within the engine system of FIG. 1;

FIG. 3 is an isometric view of a sectioned core of the heat exchanger ofFIG. 2; and

FIG. 4 is a table of example corrosion-erosion resistant coatingsapplied to the heat exchanger within the engine system of FIG. 1.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a schematic representation of anengine system 10 for marine applications, according to the presentdisclosure. The engine system 10 includes an engine 11 that includes anengine housing 21 defining an air inlet 22. The engine system 10 alsoincludes a turbocharger 12 that includes an air outlet 23 fluidlyconnected to the air inlet 22 of the engine 11 via an air line 15. Theturbocharger 12 draws ambient air through an air filter 13 and into anair inlet 44 of the turbocharger 12. Within the turbocharger 12, the airis compressed and then delivered to the engine 10 via the air line 15.An upstream portion of the air line 15 fluidly connects a fluid-handlingapparatus, being a heat exchanger 14, with the air outlet 23 of theturbocharger 12. A downstream portion of the air line 15 fluidlyconnects the heat exchanger 14 with the air inlet 22 of the engine 11.The heat exchanger 14 is also in fluid communication with a pump 18 thatcan supply sea water to the heat exchanger 14 via a sea water line 19.The heat exchanger 14 includes a heat exchanger body 24 that defines anair inlet 25, an air outlet 26, a sea water inlet 27 and a sea wateroutlet 28.

The temperature of the compressed air exiting the turbocharger 12 issignificantly increased due to the compression within the turbocharger12. Thus, the heat exchanger 14, often referred to as a charge aircooler, will cool the compressed air, via heat exchange with the seawater, before it is injected into the engine 11. Sea water is preferablyused as the coolant due to its accessibility, abundance and lowertemperatures, but it should be appreciated that the heat exchanger 10could use various other coolants. By cooling the compressed air, thedensity of the air is increased, allowing more air, and thus moreoxygen, to occupy the volume of the cylinder. When the cooled compressedair is injected into the engine 11, the increased amount of oxygenwithin the cylinder can burn, resulting in increased engine power. Theexhaust created by the combustion within the engine 11 will continue topower the turbocharger 12, and the process can repeat itself. Althoughthe present disclosure is illustrated for the engine system 10 includingthe turbocharger 12, it should be appreciated that the heat exchangercould be used for other cooling applications in engine systems with orwithout turbochargers. For instance, the heat exchanger could be used tocool hot exhaust exiting the combustion chamber of the engine.

Referring to FIG. 2, there is shown a sectioned side diagrammaticrepresentation of the heat exchanger 14. A core 30 is positioned withina space defined by the heat exchanger body 24 (shown in FIG. 1).Although the core 30 is preferably a “bar and plate” style core 30, itshould be appreciated that the present invention also contemplates theheat exchanger including a “tube and fin” style core of the type knownin the art, or any other suitable heat exchange structure. The core 30includes a core body 42 that defines a plurality of air passages 34(shown in FIG. 3) and a plurality of sea water passages 36. The corebody 42 and the heat exchanger body 24 define a sea water inlet manifold16 and a sea water outlet manifold 17 that direct sea water streams intoand out of the core 30, and a sea water middle manifold 20 that changesthe direction of the sea water flow. The sea water inlet, outlet andmiddle manifolds 16, 17 and 20, each are defined by a housing surface 16a, 17 a, 20 a and a core surface 16 b, 17 b and 20 b, respectively. Thesea water passages 36 are in fluid communication with the sea waterinlet 27 and the sea water outlet 28 via the sea water inlet manifold 16and the sea water outlet manifold 17, respectively. As illustrated bythe arrows, the sea water will flow through the inlet 27 into the seawater inlet manifold 16, through a first portion 36 a of the sea waterpassages 36 to the middle manifold 20 in which the sea water changesdirection, through a second portion 36 b of sea water passages 36 and tothe outlet 28 via the sea water outlet manifold 17. Although the seawater makes two passes through the illustrated core 30, the presentdisclosure contemplates use in heat exchangers through which the seawater makes any number of passes, including only one. It should also beappreciated that, although not shown, an air inlet manifold and airoutlet manifolds are attached to opposite ends of the core 30 to whichthe sea water manifolds 1, 17 and 20 are not attached and direct theflow of the air into and out of the air passages 34.

Still referring to FIG. 2, the heat exchanger body 24, including thecore body 42, include a plurality of wetted surfaces 43. In theillustrated heat exchanger 14, the plurality of wetted surfaces 43include, but is not limited to, the core surfaces 16 b, 17 b and 20 band the housing surfaces 16 a, 17 a and 20 a of the sea water manifolds16, 17 and 20, and surfaces defining the sea water passages 36. A firstportion 43 a of the wetted surfaces 43 are corrosion-erosion prone 43 aand a second portion 43 b of the wetted surfaces 43 arenon-corrosion-erosion prone. Those skilled in the art will appreciatethat, although all of the wetted surfaces 43 may be subjected to somecorrosion and erosion due to the harsh environment caused by the seawater, the first portion 43 a of the wetted surfaces 43 subject todirect impingement from the high velocity flow of sea water issignificantly more corrosion and erosion prone than the second portion43 b subject to contact from less turbulent flow of the sea water. Thefirst portion 43 a includes at least one sea water inlet surface 39. Thesurfaces 39 include the surfaces 16 a, 16 b and 20 a and 20 b of theinlet manifold 16 and the middle manifold 20 being that the manifolds 16and 20 direct the sea water into the sea passages 36. Preferably, thecore surfaces 17 b and the housing surfaces 17 a defining the outletmanifold 17 are also included within the first portion 43 a. Because thesea water flowing through the sea water passages 36 has a laminar flow,the sea water is not directly impinging the surfaces defining the seawater passages 36. Thus, the second portion 43 b that isnon-corrosion-erosion prone includes the surfaces of the sea water fins35 defining the sea water passages 36. Only the first portion 43 a ofthe wetted surfaces 43 is coated with a corrosion-erosion resistantcoating 40, and thus, less than all of the wetted surfaces 43 arecoated. The corrosion-erosion resistant coating 40 is harder than thecorrosion-erosion prone portion 43 a. From one point of view, thecorrosion prone surfaces are flow direction changing surfaces, whereasthe non-corrosion prone surfaces are generally parallel to the localflow direction.

Referring to FIG. 3, there is shown an isometric view of a sectionedcore 30 of the heat exchanger 14 in FIG. 2. The core body 42 includesmultiple separator sheets 32, air fins 33 and sea water fins 35,although the present invention contemplates a heat exchanger includingonly one separator sheet positioned between an air fin and a sea waterfin. The separator sheets 32 are preferably alternatively separated fromone another by the air fins 33 and the sea water fins 35 in order tomaintain the air flow separate from the sea water flow. The air fins 33separate the air passages 34 from one another, and the sea water fins 35define and separate the sea water passages 36 from one another. Thus,the sea water fins 35 include the non-corrosion-erosion prone surfaces43 b. The air fins 33 are preferably oriented substantiallyperpendicularly to the sea water fins 35 such that the flow of the airtransverses the flow of the sea water. Although it should be appreciatedthat some of the air passages and sea water passages can be oriented toone another at various angles, the air flow still transverses the seawater flow.

Further, the core body 42 includes long enclosure bars 37 that act asend surfaces for each sea water fin 35 and provide a surface forattaching the manifolds 16, 17, 20 to the core body 42. The core body 42also includes short enclosure bars 38 (shown in FIG. 2) that act as endsurfaces for each air fin 33 to protect the air fins 33 and air passages34 from sea water. Side sheets 31 enclose ends of the core 30, andmountings, such as load stops 29, are attached to the side sheets 31 toprovide a means of securing the heat exchanger 14 within the enginesystem 10. The separate components of the core 30 can be made into oneunit by various methods known in the art, such as brazing the assembledcore. Thus, the core surfaces 16 b, 17 b and 20 b (shown in FIG. 2)include surfaces of various components, including an outer surface ofthe short bars 38 separating the air fins 33 from the sea watermanifolds 16, 17 and 20, edge surfaces of the separator sheets 32, edgesurfaces of the long bars 37, and edge surfaces of the sea water fins35.

Referring to FIGS. 1-3, in the illustrated heat exchanger 14, the seawater fins 35, the separator sheets 32, the long bars 37 and the shortenclosure bars 38 are made from copper due to the heat transfercapability of the copper. Thus, the first portion 43 a beingcorrosion-erosion prone is generally made from copper. However, itshould be appreciated that the present disclosure contemplates use withcorrosion-erosion prone wetted surfaces made from metals other thancopper. The coating 40 preferably includes a metal alloy that is similarto the metal of the corrosion-erosion prone surfaces 43 a, illustratedas copper. The coating 40 preferably is sufficiently similar to thesurfaces 43 a such that the coating 40 and the corrosion-erosion pronewetted surfaces 43 a are galvanic compatible. Those skilled in the artwill appreciate that the galvanic compatibility of the coating 40 andthe surfaces 43 a is dependent on various factors, including, but notlimited to, the difference in the galvanic potentials of the coating 40and the surfaces 43 a, whether the coating 40 or the surface 43 a actsas an anode, the area of coating 40 compared to the area of theelectrolyte, and the type of electrolyte, being sea water. Although thecopper-nickel alloys set forth in FIG. 4 are slightly more noble thanthe copper surface on which they are coated, the alloys are sufficientlygalvanic compatible with the surfaces 43 a. In each of the examplecoatings set forth in Table I, the coating 40 includes a metal alloyprincipally comprised of copper.

Further, the coating 40 preferably includes a metal alloy with acoefficient of thermal expansion sufficiently similar to a coefficientof thermal expansion of the corrosion-erosion prone portion 43 a of thewetted surfaces 43 so that the coating 40 remains attached over apre-determined temperature range. The predetermined temperature range isthe range of temperatures to which the corrosion-erosion prone surfaces43 a are subjected. For instance, in the illustrated heat exchanger, thecompressed air is entering the air passages 34 at approximately 200° C.and exiting the air passages 34 at approximately 40° C. Because the airflowing through the air passages 34 transverses the core surfaces 16 b,17 b and 20 b, the sea water core surfaces 16 b, 17 b and 20 b aresubject to temperature range of 49-200° C. The coating 40 is principallycomprised of the same material as the surfaces 43 a, being copper. Thoseskilled in the art will appreciate that alloys other than copper alloys,such as certain stainless steel alloys, may be used within the coating40 applied to the copper surfaces 43 a as long as the alloy include asimilar coefficient of thermal expansion as copper.

The coating 40 is preferably 0.005 to 0.015 inches (127-381micrometers), but can have a thickness between 0.003-0.02 inches (75-500micrometers). The coating 40 should be sufficiently thick to withstandthe impingement of the sea water, but not too thick to create asubstantial heat transfer penalty, material waste and unnecessaryexpense.

Referring to FIG. 4, there is shown a table including five examplecompositions of the coating 40 applied to the heat exchanger 14.Although the coating 40 could include any type of material that isharder than the corrosion-erosion prone wetted surfaces 43 a, isgalvanic compatible with the surfaces 43 a in the relevant coolingliquid (e.g. sea water) and has a similar coefficient of thermalexpansion as the surfaces 43 a, such as certain stainless steel alloys,preferably the coating 40 includes a copper-based alloy. Preferably, thecopper-based alloy includes a copper-nickel alloy with a nickelconcentration between 9% and 40%. The copper can provide sufficient heattransfer between sea water and the air, and the nickel protects thecorrosion-erosion prone surfaces 43 a from impingement that can lead tocorrosion and erosion. The coating 40 with the nickel is harder than thecorrosion-erosion prone surfaces 43 a upon which the coating 40 isapplied. For instance, example coating 1 includes the preferred versionof the coating 40 that includes a copper-nickel alloy with a nickelconcentration of approximately 10%. Those skilled in the art willappreciate that example coating 1 is a commercially available alloy,specifically alloy 70600, often referred to as 90-10% copper nickel. Inaddition to the copper and nickel, example coating 1 includes otheralloying metals, including iron and manganese. The iron contributes thecorrosion resistance and the strength of the coating 40 a, and themanganese contributes to the stability of the coating 40 a. Moreover,because the coating 40 includes almost 90% copper, the coating 40 a issufficiently similar to the copper manifold surfaces 16 a, 16 b, 17 a,17 b, 20 a and 20 b to which the coating 40 a is applied. Thus, thecoating 40 is galvanic compatible with the surfaces 43 a, therebyproviding a stable coating 40 a even in relatively highly pollutedwaters, and will not expand at a sufficiently different rate than thesurfaces 43 a despite the heat fluctuations within the heat exchanger14. Also, example coating 1 is resistant to biological fowling inpolluted waters.

Example coating 2 includes a copper-nickel alloy that includesapproximately 70% copper and approximately 30% nickel. Those skilled inthe art will appreciate that example coating 2 is a commerciallyavailable alloy, specifically alloy 71600, often referred to as 70-30%copper-nickel. Similar to example coating 1, in addition to the copperand nickel, example coating 2 includes other alloying metals, includingiron and manganese. Example coating 2 is harder than thecorrosion-erosion prone surfaces 43 a upon which the coating 40 isapplied. Example coating 3 includes a 60% copper—40% nickel alloy.Example coating 3 is not a standard copper alloy, but rather a powdercommercially available for physical disposition spray applications.Although coating 3 could include other minor alloying metals like thoseused in example 1 and example 2, coating 3 is illustrated as including60% copper and 40% nickel. Although the coatings in examples 2 and 3will protect the corrosion-erosion prone surfaces 43 a, the 60-40%copper—nickel alloys are generally more expensive than the 90-10% coppernickel alloys, as used in example 1. Moreover, example coatings 2 and 3are less stable and more prone to fowling when coated on the coppersurfaces 43 a than the preferred coating 40 of Example 1 in highlypolluted waters.

Example coating 4 includes a 85-15% copper nickel alloy. Similar toexample coatings 1-3, example coating 4 includes copper to transfer theheat between the air and the sea water, and nickel to resistimpingement, thereby, providing corrosion and erosion resistance.Moreover, example coating 4 includes minor alloying metals and iscommercially available as alloy 72200.

Example coating 5 includes an aluminum-bronze alloy that includes 14% orless aluminum, 2% or less manganese, 6% or less nickel, and 5% or lessiron. The remaining concentration would include copper and/or otherminor alloying elements. Those skilled in the art will appreciate thatthe example coating 5 could includes standard aluminum-bronze alloyscommercially available could be used. Example coating 5 is acommercially available aluminum bronze alloy, being alloy 63000. Thealuminum aids in corrosion resistance while the iron and nickel aids inimpingement resistance. As with the other coatings 40 a-c, examplecoating 5 preferably includes manganese and iron.

INDUSTRIAL APPLICABILITY

Referring to FIGS. 1-3, a method of making the heat exchanger 14 will bediscussed. Although the heat exchanger 14 is part of the engine system10 with marine application and is a “bar and plate” type heat exchanger,those skilled in the art should appreciate that the method of thepresent disclosure could apply to various types of heat exchangers,including the “tube and fin” and “tube and shell” type, used in variousapplications. A plurality of components 32, 33, 31, 35, 37, 38, 16, 17,20 are assembled to include the plurality of wetted surfaces 43. In theillustrated example, the plurality of air fins 33 are orientedperpendicularly to the plurality of sea water fins 35, and the air fins33 and sea fins 35 are alternatively stacked and separated from oneanother with the separator sheets 32. The short bars 38 are positionedat the closed ends of the air fins 33 in order to protect the air fin 33from the incoming sea water. The components 32, 33, 31, 35, 37, 38comprising the core 30 are secured to one another generally through amethod known in the art, brazing, although the present disclosurecontemplates various methods of securing the components of the core 30to one another.

After the core 30 is brazed, the corrosion-erosion resistant coating 40is applied to less than all of the wetted surfaces 43. Thecorrosion-erosion prone surfaces 43 a are distinguished from thenon-corrosion-erosion prone surfaces 43 b, and only thecorrosion-erosion prone surfaces 43 a will be coated. Although thecorrosion-erosion prone surfaces 43 a may differ between different typesof heat exchangers, the corrosion-erosion prone surfaces 43 a includesthe wetted surface 43 that are subjected to direct impingement from thehigh velocity flow of the sea water. The non-corrosion-erosion pronesurfaces 43 b includes the wetted surfaces 43 with which the sea waterdoes not directly impinge. The surfaces 16 a, 16 b, 20 a, 20 b, 17 a and17 b are subjected to direct impingement due to the turbulent flow ofthe sea water in the manifolds 16, 17, 20 as the sea water flows intoand out of the sea water passages 36; whereas, the surfaces of the seafins 35 defining the sea passages 36 are not directly impinged by thesea water due to the laminar flow of the sea-water through the passages36. In the illustrated heat exchanger 14, the sea water makes two passesthrough the core 30. Not only will the turbulent flow of the sea waterwithin the inlet and outlet manifolds 16 and 17 cause the sea water todirectly impinge the manifold surfaces 16 a, 17 a, 16 b and 17 b beforebeing directed into and out of the sea water passages 36, the housingsurface 20 a of the middle manifold 20 directs the sea water flow fromthe first portion 36 a to the second portion 36 b of the passages 36,and thus, is also subject to direct impingement. It should beappreciated that the present disclosure could apply to heat exchangersthrough which the sea water makes any number of passes, including onlyone pass. Regardless of the number of sea water manifolds, preferablythe housing surfaces, along with the core surfaces, defining eachmanifold are coated. Thus, the coating 40 will be applied to the coresurfaces 16 b, 17 b and 20 b and the housing surfaces 16 a, 17 a and 20a, and not applied to the surfaces of the sea water fins 35 defining thesea water passages 36.

Preferably before attaching the heat exchanger body 24 to the core 30and thus creating the manifolds 16, 17 and 20, the coating 40 is appliedto the corrosion-erosion prone wetted surfaces 43 a, being the coresurfaces 16 b, 17 b and 20 b and the housing surfaces 16 a, 17 a and 20a. Because the core surface 16 b, 17 b, and 20 b are accessible afterthe core 30 is assembled and brazed, the coating 40 can be applied tothe core 30, after assembly and brazing. Thus, it is not necessary thatthe coating 40 be able to withstand the brazing process. Moreover, thecoating 40 can be applied to the housing surfaces 16 a, 17 a and 20 abefore the housing 24 is attached to the core 30. Although the coating40 can be applied by various methods, the coating 40 is preferablyapplied by thermal spraying the coating 40 on the surfaces 43 a. Thoseskilled in the art will appreciate that there are various methods ofthermal spraying. Although any one of the conventional methods ofthermal spraying could be used to coat the surfaces 43 a, preferably thecoating 40 is applied by High Velocity Oxy Fuel (HVOF). The HVOF methodallows the coating 40 to be applied with hand-held devices, including,but not limited to, spray guns, and does not require isolation in achamber or vacuum environment. Further, the coating 40 can be appliedwith a uniform thickness without the need for post treatments, such asgrinding or polishing, to only the intended surfaces, being thecorrosion-erosion prone surfaces 43 a. Thus, using proper thermal spraymethods, the coating 40 should not obstruct the assembled sea waterpassages 36. Those skilled in the art will appreciate that thecorrosion-erosion prone surfaces 43 a must be prepared and cleaned in aconventional manner when using thermal spray coating methods.

Although the thickness of the coating 40 will vary depending on thecomposition of the coating 40 and the particular application of the heatexchanger 14, the thickness will generally be between 0.003-0.02 inches(75-500 micrometers) and preferably between 0.005-0.015 inches (127-381micrometers). The coating 40 must be sufficiently thick to provide theneeded impingement and corrosion-erosion resistance, but not too thickto adversely affect cost or heat transfer.

Once the core 30 is assembled and the core surfaces 16 b, 17 b and 20 band the housing surfaces 16 a, 17 a and 20 a are coated, the core 30 canbe attached to the housing 24 in a conventional manner. The presentdisclosure contemplates various methods of attaching the core 30 to thehousing 24, including, but not limited to bolting and welding. In theillustrated embodiments, the housing 24 is welded to the core 30, andthus, the coating 40 should be able to sufficiently withstand the heatfrom the welding process. However, it should be appreciated that thejoint design style and type of the heat exchanger may be such that awelding resistant coating may not be needed. The attached housing 24 andthe core 30 define the manifolds 16, 17 and 20.

The present disclosure is advantageous because it provides a relativelyinexpensive, corrosion-erosion resistant heat exchanger 14 that can beused in harsh environments, such as in sea water. Rather than making allof heat exchanger components that come into with sea water from anexotic relatively expensive corrosion-erosion resistant material, thepresent disclosure coats only the portion 43 a of the heat exchanger 14that is most corrosion-erosion prone due to the sea water. Relativelyinexpensive materials, such as copper, that transfer heat well can stillbe used in the non-corrosion-erosion prone portions 43 b, such as thesea water fins 35. Thus, the use of the coating 40 does not adverselyaffect the efficiency of the heat exchanger 14.

The coating 40 is sufficiently hard and corrosion-erosion resistant thatthe sea water will not interact or impinge the coating 40. Thus, thecoating 40 can protect the surfaces 43 a from impingement, corrosion anderosion that can lead to holes within the surfaces 43 a, causing leakageof the sea water into the air passages 34 and premature failure. Thus,the life and durability of the heat exchanger 14 is increased by makingthe heat exchanger 14 corrosion-erosion resistant while not compromisingthe efficiency of the heat exchanger 14 or significantly increasing thecost of the heat exchanger 14. In fact, because of the increaseddurability, there is a significant decrease in heat exchanger down timeand repair frequency, which reduces maintenance costs.

The present disclosure is further advantageous because the preferredcoating 40 is stable even in highly polluted waters. Because the coating40 is made out of a similar metal as the surfaces 43 a, the coating 40is galvanic compatible with the surfaces 43 a. Moreover, even ifsubjected to extreme temperature change, the coating 40 will adhere tothe surfaces 43 a due to the similar coefficients of thermal expansionbetween the coating 40 and the surfaces 43 a.

Further, the coating 40 can be applied with relative ease. Because thecorrosion-erosion prone surfaces 43 a on which the coating 40 is neededare accessible on the assembled core 30, there is no need to apply thecoating 40 pre-assembly. Thus, there is no concern about the coating'sability to withstand the brazing of the core 30. In addition, by thermalspraying the coating 40 onto the surfaces 43 a, the coating 40 can havea uniform thickness without post-treatments, such as grinding orpolishing, thereby decreasing manufacturing costs and material waste.

It should be appreciated that, although the heat exchanger 14 isdescribed as a heat exchanger to cool compressed air exiting theturbocharger 12, the present disclosure contemplates use with any heatexchanger used for various applications and with various coolants.Further, the present disclosure contemplates use with fluid-handlingapparatuses, other than heat exchangers, that are subjected to highvelocity fluid flow.

It should further be understood that the above description is intendedfor illustrative purposes only, and is not intended to limit the scopeof the present invention in any way. Thus, those skilled in the art willappreciate that other aspects, objects, and advantages of the inventioncan be obtained from a study of the drawings, the disclosure and theappended claims.

1. A fluid-handling apparatus comprising: an apparatus body including a plurality of wetted surfaces characterized in that a first portion of the wetted surfaces is corrosion-erosion prone and a second portion of the wetted surfaces is non-corrosion-erosion prone; a corrosion-erosion resistant coating coated on the first portion of the wetted surfaces, wherein the coating is harder than the apparatus body; and wherein less than all of the wetted surfaces are coated.
 2. The fluid-handling apparatus of claim 1 wherein the coating includes a metal alloy with a coefficient of thermal expansion sufficiently similar to a coefficient of thermal expansion of the first portion of the wetted surface so that the coating remains attached over a pre-determined temperature range.
 3. The fluid-handling apparatus of claim 1 wherein the coating includes a metal alloy being galvanic compatible with the first portion of the wetted surfaces.
 4. The fluid handling apparatus of claim 1 wherein the coating includes a copper-based alloy.
 5. The fluid-handling apparatus of claim 4 wherein the coating includes copper-nickel alloys including a nickel concentration less than or equal to 40% and greater than or equal to 9%.
 6. The fluid-handling apparatus of claim 5 wherein the coating includes a nickel concentration of 9-11%.
 7. The fluid-handling apparatus of claim 4 wherein the coating includes an aluminum bronze alloy including an aluminum concentration equal to or less than 14%, a manganese concentration equal to or less than 2%, a nickel composition equal to or less than 6%, and an iron concentration equal to or less than 5%.
 8. The fluid handling apparatus of claim 1 wherein the first portion of the wetted surfaces includes at least one liquid inlet surface.
 9. The fluid-handling apparatus of claim 1 wherein the apparatus includes a heat exchanger.
 10. The fluid-handling apparatus of claim 9 wherein the heat exchanger includes an air-sea water heat exchanger.
 11. The fluid-handling apparatus of claim 10 wherein the apparatus body defines a plurality of sea water passages separated from one another by at least one sea water fin and a plurality of air passages separated from one another by at least one air fin oriented substantially perpendicular to the sea water fin, and the sea water passages being separated from the air passages by a plurality of separator plates; and the sea water passages and air passages being fluidly connected to a sea water inlet manifold and a air inlet manifold, respectively.
 12. The fluid-handling apparatus of claim 11 wherein the first portion of the wetted surfaces includes at least one sea water inlet surface within at least the sea water inlet manifold, and the second portion of the wetted surfaces includes a inner surface of the sea water passages; and the coating includes a metal alloy being galvanic compatible with the first portion of the wetted surfaces and including a coefficient of thermal expansion sufficiently similar to a coefficient of thermal expansion of the first portion of the wetted surface so that the coating remains attached over a pre-determined temperature range, and the coating including either a copper-nickel alloy with 9-40% nickel and an aluminum bronze alloy.
 13. An engine system using sea water as a coolant comprising: an engine; and a heat exchanger being in fluid communication with the engine, and defining a sea water inlet fluidly connected with a plurality of wetted surfaces, and a first portion of the wetted surfaces being corrosion-erosion prone and a second portion of the wetted surfaces being non-corrosion-erosion prone; a corrosion-erosion resistant coating being coated on the first portion of the wetted surfaces, and wherein the coating is harder than the first portion; and less than all the wetted surfaces are coated.
 14. The engine system of claim 13 wherein the first portion includes at least one sea water inlet surface of the heat-exchanger.
 15. The engine system of claim 14 wherein the coating includes a metal alloy being galvanic compatible with the first portion of the wetted surfaces and including a coefficient of thermal expansion sufficiently similar to a coefficient of thermal expansion of the first portion of the wetted surface so that the coating remains attached over a pre-determined temperature range.
 16. The engine system of claim 15 wherein the coating includes a copper-based alloy.
 17. The engine system of claim 16 wherein the coating includes a copper-nickel alloy including 9-40% nickel.
 18. A method of making a heat exchanger, comprising the steps of: assembling a plurality of components to include a plurality of wetted surfaces; distinguishing between corrosion-erosion prone wetted surfaces and non-corrosion-erosion prone wetted surfaces; and coating the corrosion-erosion prone wetted surfaces with a corrosion-erosion resistant coating being harder than the corrosion-erosion prone wetted surfaces.
 19. The method of claim 18 wherein the step of coating includes the step of thermal spraying the coating onto the corrosion-erosion prone portion of the wetted surfaces.
 20. The method of 18 wherein the step of coating being performed after the step of assembling. 